Field of the Invention
The invention relates to methods of treatment of alcoholic beverages to improve the quality thereof by contacting the beverage with compositions comprising vinyl lactam-derived polymers that exist in the form of molecular complexes with hydrogen peroxide. Particularly, the invention relates to methods of treatment of alcoholic beverages to remove one or more ingredients causing one or more undesirable sulfury and/or fatty flavors. The invention further relates to methods of treatment of alcoholic beverages to remove one or more ingredients causing one or more undesirable sulfury and/or fatty flavors and as well as one or more ingredients causing colloidal haze.
Description of Related Art
Alcoholic beverages include fermented beverages and distilled beverages. Non-limiting examples of fermented beverages include beer, cauim (made from cassava or maize), chicha (made from cassava, maize root, grape, apple or other fruits), cider (made from apple juice or other fruit juice), huangjiu (Chinese, made from rice, millet, or wheat using a special starter culture of yeast, mold, and bacteria), icariine liquor, mead (made from honey), palm wine (made from the sap of various palm trees), pulque (originally made by the natives of Mexico, made from the sap of the maguey plant), tiswin (made from corn or saguaro, a large cactus), and wine. A distilled beverage, spirit, or liquor is an alcoholic beverage containing ethanol that is produced by distilling ethanol produced by means of fermenting grain, fruit, or vegetables. Vodka, gin, baijiu, tequila, rum, whisky, brandy, and soju are non-limiting examples of distilled beverages.
Beer is an alcoholic beverage produced by the saccharification of starch and fermentation of the resulting sugar. The preparation of beer is called brewing.
More than 1,000 different flavor ingredients have been identified in beer, and more are being found as increasingly sensitive analytical methods are developed. Some of these flavors are derived from raw materials (malt, adjuncts, hops, and water), but the vast majority are formed by yeast during fermentation. Chemical and physical methods of analysis can provide a great deal of information about these ingredients; however, no instrument has been able to replace a trained taster. The physiochemical properties of a beer may be entirely within laboratory specifications, but this analysis is meaningless unless the flavor of the beer is acceptable to the drinker.
Two important tools have been developed over the past 30 years to help establish a standard vocabulary for beer sensory analysis, both by Dr. Morten Meilgaard: first, an early system based on flavor units and then, the Beer Flavor Wheel. Meilgaard developed the flavor wheel in an attempt to standardize the language of flavor analysis. The flavor wheel gives each distinct flavor a descriptive name and groups it with similar flavors into 14 classes.
Sulfury flavor is one of the descriptive names on the Beer Flavor Wheel. Some of these flavors are desirable in continental lager styles, where they complement the malty aroma. On the other hand, some are considered defects by brewers of British ales, who select the malt, yeast, and fermentation method most likely to minimize the formation of volatile sulfur compounds. Though strain-dependent, lager yeasts generally produce a much larger variety of sulfur compounds during fermentation than ale yeasts; sulfury flavors are therefore one way of distinguishing between lagers and ales. Not all sulfury flavors are formed during the normal brewing process; they can also result from bacterial contamination or poor handling. These antagonists transform sulfur compounds that otherwise are not flavor-active (such as the sulfur-containing amino acids methionine and cysteine) into undesirable off flavors such as hydrogen sulfide and mercaptans.
Sulfury flavors are caused due to the presence of one or more sulfur-containing ingredients. One of the most important sources of sulfur in beer is the sulfate ion. Sulfate ions are derived from sulfuric acid or sulfate salts and consist of a sulfur atom covalently bonded to four oxygen atoms. In nature, they are often found in combination with positively charged calcium and magnesium ions (which hydrate to form gypsum and Epsom salts, respectively).
The sulfite ion is derived from salts of sulfurous acid and consists of a sulfur atom bonded to three oxygen atoms. Sulfites and bisulfites are both strong reducing agents, capable of accepting oxygen atoms from other compounds to form sulfur dioxide and water. Most of the sulfites in beer are bound to carbonyl compounds, which diminishes both their flavor activity and their reducing capacity. A very small amount will remain free and eventually form sulfur dioxide. When present in high concentrations in beer (typically greater than 20 ppm), sulfur dioxide gives the aroma of a struck match.
Sulfidic flavors are produced by hydrogen sulfide, thiols (or mercaptans), thioesters, and related compounds. All are undesirable in beer, and all become more offensive as their concentrations increase. Hydrogen sulfide (H2S) is probably the best understood member of this group. It is a fermentation by-product with a low sensory threshold of only a few ppb. It makes its presence known by imparting to beer the aroma and taste of rotten eggs.
Thiols, also known as mercaptans, are closely related to hydrogen sulfide. The most relevant members of the thiol family in brewing are methyl-, ethyl-, and butyl-mercaptans. These compounds have aromas that may remind one of putrefied cabbage, garlic, onion, or egg. At very high concentrations they may be perceived as shrimplike.
Other sulfidic flavors attributed to mercaptans have garlic, cabbage, or burnt rubber notes. Similar flavors are associated with diethyl sulfide, diethyl disulfide, and polysulfides. These diethyl compounds are generally regarded as equivalents to dimethyl sulfide with respect to their formation in the brewing process. Polysulfides such as dimethyl trisulfide and dimethyl tetrasulfide are found in hop oils. Dimethyl trisulfide is usually destroyed by sulfur dioxide when sulfur is burnt in the oasthouse, but is slowly regenerated during storage.
Cooked vegetable flavors are generally associated with dialkyl sulfides. Dimethyl sulfide (DMS) is the most widely studied compound in this category because of its importance as a flavor constituent in lager beer styles. DMS is rarely present in isolation, but is typically coupled with other compounds such as dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and diethyl disulfide (DES).
Sulfury flavors attributable to yeast comprise both healthy yeast flavors and unpleasant off flavors resulting from yeast autolysis. Yeast autolysis produces an unmistakable rotten, rubbery, or shrimplike stench easily distinguishable from the meaty aroma of fresh yeast. Autolysis occurs under stressed conditions such as high osmotic pressure (alcohol or sugars), extremely high temperatures, long-term storage, or sudden environmental changes.
Diacetyl (2,3-butanedione) is perceived as a buttery, creamy, milky or butterscotch flavor that can occur in beer. Diacetyl is generally formed in beer from a precursor chemical produced by yeast during fermentation. It can also be formed by contaminant bacteria when hygiene standards are poor. Diacetyl is one of a class of compounds called “vicinal diketones”. Diacetyl belongs to the class of fatty flavors.
Beer stability encompasses many aspects including microbial stability, colloidal stability and flavor stability. The beer product must look good and taste good at the end of the shelf life, as it did when freshly packaged. Whilst the natural ageing of beer will adversely impact both clarity and flavor, the use of stabilizing agents can help to ensure product quality. As beer is intrinsically colloidally-unstable, without proper treatment, chill haze (non-permanent) may develop that can lead to sedimentation and precipitation (permanent haze). Beer haze results from the interaction of beer constituents that aggregate to form visible particles in solution that reflect light.
UK patent application GB 2,100,750 discloses removal of excess sulfur dioxide contained in juices, concentrates, wines, and spirits by addition of a strong solution of hydrogen peroxide.
UK patent 1,248,501 discloses a method of treating beer, comprising contacting fermented beer with a polyvinyl resin modified clay, the resin portion of the clay constituting by weight 1 to 30% of the weight of such clay. The patent further discloses that beer is treated to remove clay adsorbable proteinaceous complexes, tannins or other delirious elements.
US published patent application No. 2008/0113071 discloses compositions comprising poly N-vinyl pyrrolidone (PVPP) with improved capability to remove polyphenols and useful for reducing the formation of colloidal haze in beverages such as beer. The compositions are prepared in a process which comprises: providing a composition comprising PVPP; adding a quantity of hydrogen peroxide to the composition; generating a slurry; mixing the slurry; and removing from the slurry, the “improved PVPP”. In one embodiment, the quantity of hydrogen peroxide may bring the concentration of hydrogen peroxide in the slurry to from about 0.5% to about 5%. In another embodiment, the quantity of hydrogen peroxide may bring the concentration of hydrogen peroxide in the slurry to from about 1% to about 3%. However the process does not result in any significant amount of H2O2 complexing with the PVPP. Moreover there is no suggestion of using the “improved PVPP” for removal of hydrogen sulfide and/or diacetyl from beer.
A technical paper by Terry Robbins and Brian Boillat, published in Water & Process Technologies, GE Power & Water, reviews the chemical treatment programs available to control H2S as well as some non-sulfide odors. These include organic scavengers that react with reduced sulfur compounds, neutralizers that eliminate an odor's objectionable characteristics, nitrates and inhibitors that prevent bacteria from producing sulfides, masking agents that replace one odor with another, and metal salts that removes sulfides as metallic precipitates.
Therefore, there remains a necessity in the art for an efficient, economical and facile method of treatment for removal of ingredient(s) causing undesirable flavor(s), particularly sulfury and/or fatty off flavor(s) from alcoholic beverages, such as, beer and wine. The invention addresses this necessity.